As known, high risk pregnancies constitute about 10 to 25% of pregnancies. Among the high risk pregnancy disorders the following can be mentioned: diabetes, kidney diseases (such as chronic pyelonephritis, chronic pyelonephritis and renal insufficiency), heart diseases (such as primary pulmonary and hypertension).The known methods for controlling the progress of pregnancy, have the disadvantage of detecting the status of pregnancy disorders at a relatively late stage, when the clinical signs and symptoms are already apparent.
There are several hormone assays suggested to give an indication whether placental function is normal or to predict impending fetal death. The tests most widely used are: urine estriol, urine total estrogens, serum unconjugated estriol and serum placental lactogen. As known, estriol is an estrogenic compound produced by the placental from precursors derived from fetal adrenal cortex and fetal liver. The conjugated form of estriol is excreted into the maternal urine. Serum estriol can be measured either as total estriol or as unconjugated estriol. It usually is measured as unconjugated estriol in order to exclude maternal contribution to the conjugated fraction. Urine estriol can be measured as total estriol or as total estrogens, since estriol normally constitutes about 90% of urine total estrogens.
Estriol can be detected by immunoassay as early as the ninth week of gestation. Therefore, estriol values slowly but steadily increase until the last trimester, when there is a more pronounced increase. Clinical use of estriol measurement is based on the fact that severe acute abnormality of the fetoplacental unit, such as a dead or dying placenta, is manifested either by failure of the estriol level to continue rising or by a sudden marked and sustained decrease in the estriol level. A recent report (M.Scharf et.al. J.Obstet.Gynec.reprod. Biol., 17:365-75, 1984) concludes that in view of the low correlation between patients with abnormal serum free estriol as the antepartum pathological test, the estriol measurement can not be considered a reliable predicting tool to estimate the actual pregnancy outcome.
Urine total estrogen was the first test used, since total estrogen can be assayed by standard clinical techniques. However, urine glucose falsely increases the results and certain other substances such as urobilinogen also may interfere. On the other hand, maternal hypertension, preeclampsia, severe anemia and impaired renal function can decrease considerably urine estrogen or estriol secretion. Decrease in the level may also occur to a variable degree in a number of fetuses with severe congenital anomalies. It was also reported that continued bed-rest to the pregnant woman caused an increase in the estriol excretion values of about 20 to 30% over the levels determined from ambulatory persons. Because of the problems associated with collection of urine or serum estriol specimens and interpretation of the values, as well as the disturbing number of false positive and negative test results, most of the clinical people refrain from correlating these measurements with placental disorders. Moreover, all the previous methods did not reveal the pregnancy disorders at an early stage of their initiation, but only when the particular disease was already apparent.
It is an object of the present invention to provide a , simple method for the detection of pregnancy disorders at an early stage. It is an another object of the present invention, to provide a simple method for the detection of pregnancy disorders that has a high sensitivity. It is yet another object of the present invention to provide a simple method for the detection of pregnancy disorders, said method being not influenced by other extraneous factors related thereto.